Solvothermal Strategy Research Articles

High-performance visible-light photocatalysis induced by dye-sensitized Ti3+-TiO2 microspheres

Strong visible-light absorption and high surface areas contribute to high-perform semiconductor photocatalysis. This work aims to fabricate self-doped Ti3+-TiO2 microspheres and dye sensitized self-doped Ti3+-TiO2 composites with high surface areas and visible-light absorption via one-pot solvothermal strategy for highly enhanced photocatalytic tetracycline degradation under visible-light irradiation. The experimental results showed that the obtained Ti3+-TiO2 microspheres showed enhanced visible-light capture capacity and a larger surface area of 204.9 m2 g−1. Besides, the obtained Eosin Y/Ti3+-TiO2 composites showed efficient visible-light absorption and highly boosted photocatalytic performance towards tetracycline degradation. The highest rate constant for Eosin Y/Ti3+-TiO2-9% composite reached as high as 0.06657 min−1, approximately 8.09 times that of commercial TiO2, strongly demonstrating the significant roles of dye sensitization. Finally, a reasonable dye-sensitization visible-light photocatalytic mechanism was suggested.

Competitive coordination initiated one-pot synthesis of core–shell Bi-MOF@BiOX (X = I, Br and Cl) heterostructures for photocatalytic elimination of mixed pollutants

Core-shell Bi-MOF@BiOX (X = I, Br and Cl) hybrids were fabricated by a one-pot solvothermal strategy via regulating the concentration and type of halogen ions in the Bi-based CAU-17 synthesis. By virtue of the competitive coordination effect to Bi3+ between CAU-17 and BiOX, CAU-17 was converted into another Bi-MOF with similar structures and compositions. Moreover, Bi3+ plays the role of “bridge” and endows an intimate interface contact between BiOX and the Bi-MOF, which immensely expedites the charge and mass transportation. The obtained Bi-MOF@BiOX hierarchical heterostructures were applied to photocatalytic elimination of solo and mixed pollutants (Cr(VI)/tetracycline and Cr(VI)/o-nitrophenol), and exhibited favorable performances. Choosing Bi-MOF@BiOI as a typical example, the corresponding performances for Cr(VI) reduction, tetracycline and o-nitrophenol degradation in their solo systems are 14, 10, 8 times higher than those of CAU-17, and 13, 7, 5 times higher than those of BiOI under visible light, respectively. Of note, the above photocatalytic performances could be further improved in the coexisting environment of Cr(VI) and tetracycline or o-nitrophenol, which is attributed to the elevated charge separation efficiency caused by the timely consumption of photo-excited electrons and holes. This work gives some insights into the delicate design of MOF photocatalysts and their applications in environmental restoration.

Fe-based metal-organic framework as a chemiresistive sensor for low-temperature monitoring of acetone gas

This work demonstrates the potential of a novel iron-based metal-organic framework (Fe-MOF or VNU-15) to effectively detect low-concentration volatile organic compounds (VOCs), particularly acetone (CH3COCH3). A facile solvothermal strategy was used to synthesize Fe-MOFs, comprising Fe(II)/Fe(III) and two distinct linkers—BDC (benzene-1,4-dicarboxylate) and NDC (naphthalene-2,6-dicarboxylic acid). As a first step, Fe-MOFs were characterized to determine their pure phase formation and identify their structural and morphological characteristics. Fe-MOFs processed via the solvothermal method demonstrated high crystallinity, high thermal stability, polyhedral crystal-shaped surface morphology, and a surface area of 735 m2g−1, making them suitable for gas-sensing applications. Laboratory-scale gas-sensing devices were fabricated by printing Fe-MOF powder onto patterned interdigitated electrodes, with performance measurements conducted on these devices in response to exposure to various target gases at temperatures between 25 and 200 °C and gas concentrations between 1 and 10 ppm. Gas-sensing tests confirmed that the VNU-15 sensor selectivity detects CH3COCH3 with a gas response of 1.68–10 ppm and a response time of 64 s, followed by a recovery time of 166 s at 50 °C. This study demonstrates the feasibility of using novel MOF-based sensing channels as low-temperature gas sensors, providing new insights into gas-sensing technology.

Adsorption‐Induced In‐Situ Construction of TiO2 Hollow Sphere/UiO‐66‐NH2 Heterostructures with Boosted Photocatalytic Activity toward Cr(VI) Reduction

AbstractWater contamination caused by highly toxic Cr(VI) should be resolved imminently with a more efficient photocatalytic approach. The interaction between photocatalyst heterostructure is critical for charge separation which largely affects the photocatalytic efficiency. Herein, TiO2 hollow sphere/UiO‐66‐NH2 (TiO2/UiO‐66‐NH2) heterostructures were successfully synthesized by an adsorption‐induced in‐situ solvothermal growth strategy. The UiO‐66‐NH2 particles were well dispersed on TiO2 hollow spheres by solvothermal treatment of Zr4+ adsorbed TiO2 hollow spheres with NH2‐BDC ligand. The photocatalytic activities of TiO2/UiO‐66‐NH2 heterostructures were investigated by reduction of Cr(VI) with visible light irradiation. With the introduction of UiO‐66‐NH2, the reduction efficiency toward Cr(VI) by TiO2/UiO‐66‐NH2 heterostructures reached 89% after 180 min of irradiation, which is much higher than those of TiO2 hollow spheres (10%) and UiO‐66‐NH2 crystals (29%). Moreover, the TiO2/UiO‐66‐NH2 heterostructures display good regeneration ability and can still maintain 70% of Cr(VI) removal ability after four cycles. The integration of TiO2 and UiO‐66‐NH2 could construct a type‐II heterojunction to broaden the absorption range of light and suppress the recombination of photoproduced electrons and holes. As a result, such unique composite structure significantly enhance the photocatalytic performance towards Cr(VI) reduction. This work not only inspires a new approach for in‐situ solvothermal synthesis of semiconductor@MOFs composites, but provides a novel photocatalyst for highly efficient removal of Cr(VI) from wastewater.

2D/2D Carbon Nitride/Zn-Doped Bismuth Vanadium Oxide S-Scheme Heterojunction for Enhancing Photocatalytic CO2 Reduction into Methanol

Developing superior photocatalytic CO2 conversion systems for the generation of high-valued fuels or chemicals is highly desirable but is still challenging work. Herein, the well-organized carbon nitride/Zn-doped bismuth vanadium oxide (CN-ZnBVO) nanohybrids were constructed by a facile CTAB-assisted solvothermal strategy to achieve an efficient photocatalytic reduction of CO2 to CH3OH under UV–vis light. Impressively, the distinctive butterfly-like 2D/2D CN-ZnBVO catalyst showed markedly enhanced photocatalytic performance in alkaline medium, with the largest CH3OH generation rate of 609.1 μmol g–1 h–1 and a high selectivity of 90.5%, outperforming most recently reported CO2 photoreduction systems. Moreover, the yield of CH3OH remained nearly constant over three successive repeated cycles, signifying its good stability. Detailed characterization and theoretical calculations revealed that the outstanding photocatalytic activity owes much to the more accessible reaction sites and improved CO2 absorption capacity induced by the distinctive micromorphology effect, as well as the localized charge density distribution and fast spatial charge separation and transfer caused by the 2D/2D S-scheme heterojunction, thus providing more photogenerated electrons for efficient CH3OH formation. The present work offers a new perspective for the in situ construction of highly active S-scheme heterostructures for selective photocatalytic CO2 reduction.

Ferrocene‐Based Actinide Clusters: Synthesis, Crystal Structures, and Characterization

AbstractThe polynuclear metal clusters continually attract wide interest due to their intriguing structures and potential applications in various scientific fields. Here, four actinide clusters have been synthesized by the utilization of multifunctional ligand ferrocenecarboxylic acid (HFcc) and Th4+/U4+ ions by solvent evaporation or solvothermal synthesis strategies in different solvents. Therein, compounds 1, 2 and 4 feature similar [An6(μ3‐O)4(μ3‐OH)4]12+ cores, which are further coordinated by 12 Fcc− ligands and different solvent molecules. The U6Fe12 cluster of compound 4 is linked by four free HFcc molecules via multiple hydrogen bonding to form a supramolecular cluster [U6(μ3‐O)4(μ3‐OH)4(Fcc)12(H2O)4] ⋅ 4HFcc. The cluster core of compound 3 is a μ3‐O2− bridged [U3(μ3‐O)]10+ unit, which is further coordinated by 10 Fcc− ligands via three kinds of coordination modes. It is worth noting that multifunctional Fcc− ligand not only endows compound 1 a main redox wave at E1/2=0.720 V in CH2Cl2/DMF solution, but also enables it to exhibit aggregation‐induced emission (AIE) property.

Adjacent diatomic Cu1N3/Mo1S2 entities decorated carbon nitride for markedly enhanced photocatalytic hydrogen generation

The regulation of the electronic structure of graphitic carbon nitride (CN) has been considered as one of the most promising methods to improve its photocatalytic efficiency. However, how to adjust effectively the electronic structure remains a great challenge. Herein, we pioneered a microwave-assisted solvothermal sulphidation strategy for the preparation of Cu1N3-linked Mo1S2 adjacent diatomic entities decorated CN (Cu1N3/Mo1S2/CN) through the enabled sulphidation around single Cu atom by the super hot spots owing to the localized surface plasmon resonance effect. The electronic structure of CN is regulated by the synergistic effect of the adjacent diatomic metal Cu and Mo, which not only makes the conduction band of the catalyst closer to the Fermi level, but also improves the charge transfer of CN. As a result, Under visible light irradiation and atmosphere conditions, the H2 generation rate (HER) of the Cu1N3/Mo1S2/CN catalyst reaches as high as 6.14 mmol g-1h−1, which is 85 times higher than that onbulk CN. It was highlighted that the introduced Cu1N3-linked Mo1S2 adjacent diatomic entities act as modulator to efficiently tune the electronic structure of the CN semiconductor, rather than as active sites, and for all samples, the deposited Pt is requested to act as active sites for H2 production. This work not only provides enlightenment for the development of an outstanding non-precious metals modified CN-based photocatalyst for solar hydrogen production, but also provides a new avenue for the design of diverse adjacent diatomic catalysts towards various transformations.

Improved utilization of Cu0 for efficient adsorption of iodine in gas and solution by mesoporous Cu0-SBA-15 via solvothermal reduction method

Cu-based materials have been considered as good adsorbents for iodine adsorption. However, the development of Cu-based adsorbent with high Cu utilization remains a significant challenge. Herein, we report a new Cu0-SBA-15 adsorbent with high Cu utilization for high capacity adsorption of iodine in gas and solution. An improved solvothermal reduction strategy was proposed to fabricate Cu0-SBA-15 composite with high Cu utilization. The benefit of the strategy was that the Cu0 nanoparticles were confined on the surface or pore wall of mesoporous SBA-15, which improved the utilization of adsorption sites for iodine. The results demonstrated that the obtained Cu0-SBA-15 composite showed high adsorption capacities of 954 mg/g and 842 mg/g for iodine in gas and solution, respectively, and reached a record high Cu utilization of 96.93%. The obtained Cu0-SBA-15 composite showed high thermal stability. Furthermore, the iodine adsorption mechanism was that Cu0 reacted with I2 to form stable CuI. Owing to the excellent adsorption performance, the obtained Cu0-SBA-15 might be potential promising iodine adsorbent.

Framing of Poly(arylene-ethynylene) around Carbon Nanotubes and Iodine Doping for the Electrochemical Detection of Dopamine.

Dopamine (DA), an organic biomolecule that acts as both a hormone and a neurotransmitter, is essential in regulating emotions and metabolism in living organisms. The accurate determination of DA is important because it indicates early signs of serious neurological disorders. Covalent organic frameworks (COFs) and metal-organic frameworks (MOFs) have received considerable attention in recent years as promising porous materials with an unrivaled degree of tunability for electrochemical biosensing applications. This study adopted a solvothermal strategy for the synthesis of a conjugated microporous poly(arylene ethynylene)-4 (CMP-4) network using the Sonagashira-Hagihara cross-coupling reaction. To increase the crystallinity and electrical conductivity of the material, CMP-4 was enveloped around carbon nanotubes (CNTs), followed by iodine doping. When used as an electrochemical probe, the as-synthesized material (I2-CMP-CNT-4) exhibited excellent selectivity and sensitivity to dopamine in the phosphate-buffered solution. The detection limits of the electrochemical sensor were 1 and 1.7 μM based on cyclic voltammetry (CV) and differential pulse voltammetry (DPV).

Nanoengineering modification of Ni-YSZ anode using in-situ solvothermal process in solid oxide fuel cells with internally reformed fuel

The conventional Ni-Y0.16Zr0.84O1.92 anode in solid oxide fuel cells fueled with hydrocarbon fuels is prone to suffer from carbon deposition. In this work, we employed an in-situ solvothermal method to decorate the Ni-Y0.16Zr0.84O1.92 anode with Gd0.1Ce0.9O1.95-δ nanoparticles to improve its resistance to carbon deposition and thus improve the electrochemical performance of the cell. This method generates small Gd0.1Ce0.9O1.95-δ particles and at the same time does not block the gas diffusion channels. The Gd0.1Ce0.9O1.95-δ-decorated anode showed enhanced long-term stability in methane with no significant performance degradation after 700 at 750 °C, whereas an untreated Ni-Y0.16Zr0.84O1.92 anode only worked for less than 8 h under the same conditions. The addition of Gd0.1Ce0.9O1.95-δ nanoparticles was found to enhance internal reforming reactions of methane by the distribution of relaxation times technique. This work demonstrated that in-situ solvothermal modification strategy can provide anodes with excellent carbon deposition resistance.

A spiral shape microfluidic photoreactor with MOF(NiFe)-derived NiSe-Fe3O4/C heterostructure for photodegradation of tetracycline: Mechanism conception and DFT calculation

Tetracycline (TC), as a high-world consumption antibiotic, has a stable molecular structure and low biodegradability, which makes it highly demanding to be removed. Herein, we propose a viable solvothermal strategy for the synthesis of flower-like NiSe-Fe3O4/C S-scheme heterostructure from the hierarchical Ni/Fe-MOF sacrificial template and its application to the photocatalytic degradation of TC in a designed spiral shape microfluidic photoreactor. The electrochemical, optical, microscopic, density functional theory (DFT) calculations, and experimental results, have thoroughly confirmed that coupling of the NiSe-Fe3O4 heterostructure and carbon sheath can promote superior light-harvesting ability and photoexcited charge separation and transfer efficiency, resulting in robust photocatalytic performance. The photocatalytic degradation efficiency of TC was reached more than 85% in 15 min by NiSe-Fe3O4/C. Moreover, detailed mechanism evaluation admits the crucial effect of the produced reactive oxygen species (OH and O2−) leads to significant performance. This work provides new insight into the rational design of bi-MOF-derived S-scheme heterostructure with an internal electric field that derives charge separation and transfer. In addition, the rate of mass transfer in photocatalytic reaction is facilitated by proposing microfluidic systems as a capable process and intensification strategy toward environmental remediation applications.

Bifunctional Nanostructured Palladium/MoSx Electrocatalyst for Cathode Hydrogen Evolution Reaction PEM Water Electrolysis and Oxygen Reduction Reaction

AbstractThe creation of effective Pd‐based architectures with numerous electrocatalytic active sites and efficient charge transfer is of key importance for improving the electrocatalytic performance in water electrolyzer and fuel cell applications. On the other hand, MoS2, possessing multiple electrocatalytic active sites, can act both as support and booster to Pd‐based electrocatalytic structures. Herein, MoSx@Pd hybrids were successfully synthesized by using a one‐pot liquid phase solvothermal strategy with stoichiometric excess of Pd. The optimized MoSx@Pd proves to be an excellent bifunctional electrocatalyst for both hydrogen evolution reaction and oxygen reduction reaction (ORR). Optimized MoSx@Pd operates the process for hydrogen evolution at the same potential as Pt/C and achieves a low overpotential of 76 mV at −10 mA cm−2 due to improved reaction kinetics and charge transfer processes between Pd and MoS2. On top of that, MoSx@Pd exhibits excellent performance and stability as cathode electrocatalyst in a polymer electrolyte membrane water electrolyzer. Simultaneously, the bifunctional electrocatalyst shows enhanced electrocatalytic ORR activity and stability by maintaining 93% of its initial activity outperforming commercial Pt/C. Finally, rotating ring disk electrode analysis reveals that ORR proceeds through the energy efficient 4e− pathway, with water being the main product, rendering MoSx@Pd a promising component for fuel cells.

In Situ Construction of BiO(ClBr)(1-x)/2Ix-n Solid Solution with Appropriate Surface Iodine Vacancies for Synergistically Boosting Visible-Light Photo-Oxidation Capability.

A proposed BiO(ClBr)(1-x)/2Ix-n solid solution containing abundant iodine vacancies has been constructed through a facile solvothermal treatment strategy. Fascinatingly, the iodine-vacancy BiO(ClBr)(1-x)/2Ix-n solid solution exhibits an outstanding visible-light photocatalytic degradation property for the environmentally hazardous pollutants of methyl orange, tetracycline, and phenol solutions, which is credited to the synergistic effect of iodine vacancies and the solid solution. By manipulating the molar ratios of Cl, Br, and I, the band structure of the solid solution attained is controlled, enabling the samples to maximize the harvest of visible light and to possess strong oxidation features. More importantly, the construction of iodine vacancies is bound to modulate the local surface atomic structure and promotes the efficiency of the separation of photogenerated carriers. Given these, the microstructure and physicochemical and photoelectrochemical properties of the photocatalysts are fully characterized in a series. In addition, the iodine-vacancy BiO(ClBr)(1-x)/2Ix-n solid solution has a stable crystal structure that permits favorable recyclability even after multiple cycles of degradation. This study sheds light on the significance of the simultaneous existence of vacancy and the solid solution for the enhanced performance of photocatalysts and opens up new insights for sustainable solar-chemical energy conversion.

One-pot synthesis of fluorescent aminoclay and the ratiometric fluorescence detection of sunset yellow

Herein, a facile one-pot solvothermal strategy was utilized for fabrication of fluorescent aminoclay (F-AC) using MgCl2, 3-aminopropyltrimethoxysilane and m-phenylenediamine as precursors. This approach provides a simple approach for scale-up synthesis of F-AC. The as-prepared F-AC exhibited blue-green fluorescence and good photostability. And pH significantly affects the fluorescence emission behavior of F-AC, and F-AC showed the strongest fluorescence at pH = 4.0. The fabricated F-AC was utilized for ratiometric fluorescence determination of sunset yellow with good sensitivity by virtue of the ratiometric fluorescence varies at 535 nm and 490 nm, and a linear relationship in the range of 0–30 μM was obtained with a LOD of 0.195 μM. Furthermore, the F-AC was utilized for anti-counterfeiting and fabricated as fluorescent gel and membrane, revealing the promising optical applications of F-AC.

MXene-derived Ti3C2 quantum dots-based ratiometric fluorescence probe for ascorbic acid and acid phosphatase determination

As a burgeoning zero-dimensional nanomaterial, MXene quantum dots which are derived from two-dimensional transition-metal carbides have attracted a lot of interest lately. The transformation of two-dimensional MXene into zero-dimensional structures of a few nanometers enables these recently discovered materials to possess an exceptional quantum size effect and remarkable photoluminescence characteristics. Hence, we synthesized N doped Ti3C2 MXene quantum dots (N-Ti3C2 MQDs) exhibiting bright blue fluorescence through small-molecule amine-assisted solvothermal strategy. In this work, we constructed a novel ratiometric fluorescence biosensor for the determination of ascorbic acid (AA) and acid phosphatase (ACP) based on the excellent optical performance of N-Ti3C2 MQDs and combined o-phenylenediamine (OPD). This ratiometric strategy was established based on the inner filter effect between N-Ti3C2 MQDs and the oxide of OPD. Sensitive fluorometric analyses of AA and ACP were achieved successfully in the respective ranges of 2–240 μM and 0.15–3.75 U/L with respective limits of detection down to 0.82 μM and 0.02 U/L. Moreover, the response time of this fluorescence sensor for AA and ACP determination was less than 1.5 h. The intraday and interday relative standard deviations for AA and ACP assay were all below 8.3 %, suggesting the good reproducibility of this sensor. In addition, the profuse color changed under UV light with analytes concentrations increased and exhibited great potential for visual detection and on-site application. The proposed method was further utilized to screen of potential ACP inhibitors, indicating that this probe has great potential in clinical practice.

Guest Editorial: Solar Energy Utilization

Guest Editorial: Solar Energy Utilization

In situ synthesis of CdS@NH2-MIL-125 nanocomposite for the enhanced photocatalytic oxidative desulfurization of dibenzothiophene

CdS@NH2-MIL-125 nanocomposite was synthesized via an in situ solvothermal strategy, fully characterized and investigated as a photocatalyst for oxidative desulfurization of dibenzothiophene.

A bimetallic metal-organic framework with high enzyme-mimicking activity for an integrated electrochemical immunoassay of carcinoembryonic antigen.

Metal-organic frameworks (MOFs) show excellent catalytic activity and have been widely applied in diagnosis of diseases and tumors. However, current assay methods usually involve cumbersome configurations and complicated procedures, which inhibit their practical applications. Hence, a Cu-Ni MOF/carbon printed electrode (CPE)-based integrated electrochemical immunosensor was constructed for highly sensitive and efficient determination of carcinoembryonic antigen (CEA). First, highly conductive carbon ink was screen-printed onto a polyethylene terephthalate substrate to manufacture a CPE. Afterward, an aminated Cu-Ni MOF was prepared by a typical solvothermal strategy and modified on the CPE. Owing to its excellent peroxidase activity, the Cu-Ni MOF can catalytically oxidize hydroquinone using hydrogen peroxide, which greatly amplifies the peak current signal. Then the formation of an immune complex inhibited the catalytic activity of the MOF, thus enabling the quantitative determination of CEA content with a wide linear range of 0.5 pg mL-1-500 ng mL-1 and a low detection limit of 0.16 pg mL-1. Furthermore, the Cu-Ni MOF/CPE-based integrated portable electrochemical immunosensor also showed satisfactory performance in the detection of CEA in clinical serum samples with excellent accuracy, showing great potential for application in point-of-care disease diagnosis.

Hierarchical mesoporous binary nickel cobalt selenides nanospheres for enhanced sodium-ion storage

Owing to high theoretical specific capacity, transition metal selenides as prospective anode materials for sodium-ion batteries (SIBs) have caused extraordinary concern. However, the poor electrochemical property caused by the large volume changes and relatively low electrical conductivity limits their practical application. Herein, uniform Ni0.33Co0.67Se2 nanosphere with hierarchical mesoporous structure was synthesized successfully through a feasible solvothermal selenization strategy. The unique hierarchical mesoporous nanostructure and enhanced electrical conductivity from binary metal selenide combination result in excellent Na+ storage performance. The as-prepared Ni0.33Co0.67Se2 anode material delivers ultra-long cycling life (301.9 mAh g−1 after 1300 cycles at 1.0 A g−1 with low per-cycle capacity decay ∼ 0.062 mAh g−1) and excellent rate capability (314.5 mAh g−1 at 8.0 A g−1) for SIBs. Besides, the quantitative kinetic analysis results indicate the superior Na+ storage performance of the Ni0.33Co0.67Se2 electrode might be imputed to the dominant pseudocapacitive behavior. These results prove the binary nickel cobalt selenides have great potential as anode materials for SIBs.

A Thermally Promoted Homogenous-Floating-Concentrating Strategy Synthesizing Highly Crystalline Triazine/hydroxyl-Rich COFs for 4-Nitrophenol Adsorption.

In this work, a "thermally promoted homogenous-floating-concentrating" strategy is reported for the rapid synthesis of highly crystalline triazine/hydroxyl-rich COFs under mild conditions, using for the effectively adsorbing 4-nitrophenol (4-NP) in aqueous solutions. This strategy originates from an optimized "homogenous-floating-concentrating" method as reported in the previous work. Both gradually improving concentration and heat treatment promote the condensation reaction between amino and aldehyde groups, resulting in high crystallinity and shorter reaction time. The obtained COFs demonstrate better crystallinity and higher surface area in comparison with the counterparts prepared by solvothermal strategy. A maximum surface area of 2391 m2 g-1 is achieved. The COFs exhibit excellent 4-NP adsorption capacity (Qmax = 1402.0mg g-1 ), which is attributed to abundant triazine/hydroxyl-groups on the COF skeleton and their strong H-bonding interaction with 4-NP.